Despite heavy rain to the north, only minor flooding expected along Rock River

JANESVILLE—Widespread, gully-washing rains on Monday dumped between 2 and 6 inches of rain into the Rock River basin, but weather forecasters expect only minor river flooding in Rock County.

On Tuesday, river gauges on the Rock River at Afton and Lake Koshkonong showed water levels within 6 inches of reaching minor flood stage. Forecasters expect the river to peak Friday at 9.1 feet at Afton and 10.3 feet at Lake Koshkonong.

That means low-lying farm fields along the river likely will get swamped with floodwaters.

More rain is expected later this week, but unless the area sees continued heavy rainfall, forecasters say it's unlikely flooding this spring could approach anything close to floods of 2008 and 2013.

According to National Weather Service data, Rock County had 2.3 inches of rain Tuesday. Areas along the Rock River farther north, such as Watertown, saw nearly 6 inches of rain.

All that water is moving downhill toward Rock County, but Rudy Schaar, a meteorologist at the National Weather Service's Sullivan office, said the Rock River can mostly handle it.

“We were lucky. The river has been on the high side, but it was mostly within its banks before the Tuesday rain event started,” Schaar said.

He said rains expected later this week are factored into the predicted crest later this week.

“If we get the next round (of rain) that's predicted on Thursday, if we get some thunderstorms that cause a few more gully washers in the basin, it could get more significant, but right now, it's nothing major,” he said.

Rock County residents have been getting accustomed to the annual threat of floods.

In April and May 2013, Rock County had 13 inches of rain, most of which happened in a span of about two weeks in early April. That caused major flooding in Rock County, where floodwaters on the Rock River reached 11.5 feet at Lake Koshkonong and Afton.

So far this spring, Rock County has only seen about half that amount of rainfall.

In 2008, when the Rock River surged to a record high 13.5 feet at Afton, 21 inches of rain fell between April and June. That came after a winter during which the area recorded 84 inches of snowfall.

“That year, the snow melted rapidly. Then, there was a very wet spring and early summer. Basically, the whole area started out as very saturated, and river levels were high to start with. There was no place for the water to go," Schaar said.

This past winter, Rock County had 60 inches of snow, but Schaar said the snow melted much more slowly.

Rock County Chief Deputy Barb Tillman said the sheriff's office plans to have patrols monitoring river levels every day this week.

“You look at past history of flooding, but you have to go out and look in the field to get firsthand knowledge,” she said.

Weather patterns may be different every spring, Tillman said, but what doesn't change is the fact that water runs downhill.

“We're kind of watching Jefferson County to see how (heavier rains there) could impact Rock County,” she said.

Tillman said the sheriff's office emergency management department has planned to meet with officials in the town of Milton, town of Fulton and Afton on Wednesday to form a plan in case any areas along the river need sandbagging.

“As it stands, we're in good shape. We've got a supply of sandbags on hand, and we're working with the town chairs to make sure we can meet all their needs,” Tillman said.